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<DIV>For all the reasons offered earlier in this and the preceding threads
"Digital Locations" and "place names," I agree that numerical reference systems
are a useful way to describe the location of a geographic feature independent of
changing boundaries and landscapes. As such, it is an item of information
(evidence, when relevant to an issue) that needs a citation to its source--a
sextant reading, GPS instrument, map measurement, GoogleMaps solution,
or&nbsp;an original source cited elsewhere.</DIV>
<DIV>
<DIV>&nbsp;</DIV>
<DIV>I do have a problem with&nbsp;"digital location" as an alternative to "GPS
location". "Digital location," like the more&nbsp;descriptive "geodetic
location," is a generic term applicable to&nbsp;different numerical reference
systems for precisely designating points on the ground.&nbsp;Besides GPS (which
is not a rectangular grid, and as noted earlier, differs slightly&nbsp;from
latitude and longitude&nbsp;measured from the&nbsp;traditional meridian through
the Greenwich Observatory, being based on a line 5.31 seconds of arc to the
east, or 102.5 meters at the latitude of the observatory), &nbsp;there are a
number of other digital systems
for&nbsp;designating&nbsp;geographic&nbsp;locations by numerical reference to a
rectangular grid on a projected&nbsp;flat surface, known as plane coordinate
systems. The most common is the UTM or Universal Transverse Mercator grid, with
locations designated by distance in meters&nbsp;on x and y axes from&nbsp;an
origin point in each of its 18 east-west zones.&nbsp;Other
systems,&nbsp;commonly use&nbsp;in land surveying,&nbsp;are the
older&nbsp;legally-adopted state plane coordinate systems, with locations
designated in feet north and east from the origin of each state's grid.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Note that the GPS designates a location on the most recent calculation of
the&nbsp;earth's spheroidal surface in relation to its axis and equator. A GPS
designation as a reference to&nbsp;a particular&nbsp;land location is subject
to&nbsp;change as the continental plates shift with tectonic drift. The
precision of the GPS system will now allow&nbsp;these changes to be observed and
measured over the years (and the aiming points for intercontinental missiles
adjusted accordingly).</DIV>
<DIV>&nbsp;</DIV>
<DIV>Donn
<DIV>&nbsp;</DIV>
<DIV><FONT lang=0 size=2 face=Arial FAMILY="SANSSERIF" PTSIZE="10">Donn Devine,
CG, CGL<BR>Wilmington DE <BR><BR>CG, Certified Genealogist, CGL, and Certified
Genealogical&nbsp;Lecturer are service marks of the Board for Certification of
Genealogists, used under license by board certificants after periodic
evaluation, and the board name is registered in the US Patent &amp; Trademark
Office.</FONT></DIV></DIV></DIV></FONT></BODY></HTML>